Sensor apparatus, control system having the same and offset correction method

Abstract

Each acceleration sensor of an air bag system includes a sensing device, a communication device and an adjusting device. The sensing device generates a measurement signal, which indicates a measurement value of acceleration. The communication device performs two-way communication relative to a master ECU and each remaining one of the acceleration sensors of the air bag system. The adjusting device adjusts the measurement value based on a physical quantity application state of its own acceleration sensor and a physical quantity application state of each remaining one of the acceleration sensors.

1. A control system comprising:
 a plurality of sensor apparatuses, each of which measures a corresponding physical quantity of a measurement subject and outputs a measurement value of the measured physical quantity; and 
 a control apparatus that outputs an offset correction command to each of the plurality of sensor apparatuses to execute offset adjustment on an offset value of the measurement value in each required one of the plurality of sensor apparatuses, which requires the offset adjustment, wherein each sensor apparatus includes:
 a sensing device that generates a measurement signal, which changes in consistent with a change in the physical quantity of the measurement subject and indicates the measurement value of the measured physical quantity; 
 a communication device that performs two-way communication relative to the control apparatus and each remaining one of the plurality of sensor apparatuses, wherein the communication device receives the offset correction command from the control apparatus, and the communication device outputs measurement information, which includes the measurement value indicated by the measurement signal generated from the sensing device of its own sensor apparatus, to each remaining one of the plurality of sensor apparatuses and receives the measurement information from each remaining one of the plurality of sensor apparatuses; and 
 an adjusting device that adjusts the measurement value, which is indicated by the measurement signal received from the sensing device of its own sensor apparatus, wherein: 
 the adjusting device determines a physical quantity application state of the sensing device of the own sensor apparatus based on the measurement value, which is indicated by the measurement signal received from the sensing device of the own sensor apparatus, in response to the offset correction command received from the control apparatus through the communication device of the own sensor apparatus; 
 the adjusting device determines whether the physical quantity is applied to the sensing device of the own sensor apparatus based on the physical quantity application state of the sensing device of the own sensor apparatus, which is obtained based on the measurement value of the sensing device of the own sensor apparatus, and a physical quantity application state of the sensing device of each remaining one of the plurality of sensor apparatuses, which is obtained based on the measurement value included in the measurement information received from the remaining one of the plurality of sensor apparatuses through the communication device of the own sensor apparatus; and 
 the adjusting device executes the offset adjustment of the offset value of the measurement value, which is indicated by the measurement signal received from the sensing device of the own sensor apparatus, when the adjusting device determines that the physical quantity is not applied to any of the sensing devices of the plurality of sensor apparatuses. 
 
 
   
   
     2. The control system according to  claim 1 , wherein the adjusting device of each sensor apparatus includes:
 an offset value obtaining means for obtaining the offset value of the measurement value, which is indicated by the measurement signal generated from the sensing device of the own sensor apparatus, when the offset value obtaining means receives the offset correction command from the control apparatus through the communication device of the own sensor apparatus; 
 a condition determining means for making a determination of whether the offset value of the measurement value obtained by the offset value obtaining means of the own sensor apparatus satisfies a physical quantity application state determination condition, which indicates the physical quantity is not applied to the sensing device of the own sensor apparatus, and for obtaining a result of the determination as a physical quantity application state; 
 a determination result outputting and receiving means for outputting the physical quantity application state, which is obtained by the condition determining means of the own sensor apparatus, to each remaining one of the plurality of sensor apparatuses through the communication device of the own sensor apparatus and also for receiving through the communication device of the own sensor apparatus the physical quantity application state of each remaining one of the plurality of sensor apparatuses, which is obtained by the condition determining means of the adjusting device of the remaining one of the plurality of sensor apparatuses; 
 a determination result comparing means for determining whether the offset value of the measurement value of the own sensor apparatus needs to be corrected based on the physical quantity application state of the own sensor apparatus and the physical quantity application state of each remaining one of the plurality of sensor apparatuses; and 
 an offset adjusting means for adjusting the offset value of the measurement value of the own sensor apparatus in such a manner that the offset value of the measurement value, which is indicated by the measurement signal outputted from the sensing device of the own sensor apparatus in a state where the physical quantity is not applied to the sensing device of the own sensor apparatus, becomes substantially zero when the determination result comparing means determines that the offset value of the measurement value of the own sensor apparatus needs to be corrected. 
 
   
   
     3. The control system according to  claim 2 , wherein the determination result comparing means determines whether the offset value of the measurement value of the own sensor apparatus needs to be corrected based on the physical quantity application states of the plurality of sensor apparatuses, each of which has a common measurement direction of the sensing device thereof for measuring the physical quantity. 
   
   
     4. The control system according to  claim 1 , wherein the adjusting device of each sensor apparatus includes a notifying means for notifying completion of the offset adjustment on the offset value of the measurement value of the own sensor apparatus to the control apparatus after completion of the offset adjustment. 
   
   
     5. The control system according to  claim 1 , wherein each of the plurality of sensor apparatuses is paired with another one of the plurality of sensor apparatuses such that a first one of the two sensor apparatuses of each pair is for making a main determination, and a second one of the two sensors of each pair is for making a supplementary determination, and the first one and the second one of the two sensor apparatuses of each pair execute the offset adjustment at different time points, respectively. 
   
   
     6. A sensor apparatus that serves as one of a plurality of sensor apparatuses of a control system to measure a corresponding physical quantity of a measurement subject and to output a measurement value of the measured physical quantity, wherein a control apparatus of the control system outputs an offset correction command to each of the plurality of sensor apparatuses to execute offset adjustment on an offset value of the measurement value in each required one of the plurality of the sensor apparatuses, which requires the offset adjustment, the sensor apparatus comprising:
 a sensing device that generates a measurement signal, which changes in consistent with a change in the physical quantity of the measurement subject and indicates the measurement value of the measured physical quantity; 
 a communication device that performs two-way communication relative to the control apparatus and each remaining one of the plurality of sensor apparatuses, wherein the communication device receives the offset correction command from the control apparatus, and the communication device outputs measurement information, which includes the measurement value indicated by the measurement signal generated from the sensing device of its own sensor apparatus, to each remaining one of the plurality of sensor apparatuses and receives the measurement information from each remaining one of the plurality of sensor apparatuses; and 
 an adjusting device that adjusts the measurement value, which is indicated by the measurement signal received from the sensing device of its own sensor apparatus, wherein: 
 the adjusting device determines a physical quantity application state of the sensing device of the own sensor apparatus based on the measurement value, which is indicated by the measurement signal received from the sensing device of the own sensor apparatus, in response to the offset correction command received from the control apparatus through the communication device of the own sensor apparatus; 
 the adjusting device determines whether the physical quantity is applied to the sensing device of the own sensor apparatus based on the physical quantity application state of the sensing device of the own sensor apparatus, which is obtained based on the measurement value of the sensing device of the own sensor apparatus, and a physical quantity application state of the sensing device of each remaining one of the plurality of sensor apparatuses, which is obtained based on the measurement value included in the measurement information received from the remaining one of the plurality of sensor apparatuses through the communication device of the own sensor apparatus; and 
 the adjusting device executes the offset adjustment of the offset value of the measurement value, which is indicated by the measurement signal received from the sensing device of the own sensor apparatus, when the adjusting device determines that the physical quantity is not applied to any of the sensing devices of the plurality of sensor apparatuses. 
 
   
   
     7. The sensor apparatus according to  claim 6 , wherein the adjusting device adjusts a self-diagnosis output value, which is outputted from the communication device of the own sensor apparatus to each remaining one of the plurality of sensors.